1. Field of the Invention
The present invention relates to a light emitting apparatus that covers the side surface of a light emitting device with light reflective resin, and a method for producing this light emitting apparatus.
2. Description of the Related Art
Semiconductor light emitting elements such as light emitting diodes (LED) and laser diodes (LD) have been used in various types of light sources. In recent years, light emitting diodes have received attention as light sources for fluorescent lamps due to their long life and low power consumption. Further improvement of light emitting diodes is required in light output and light emission efficiency. Also, a light emitting diode light source is required which has high brightness and a particular light distribution (e.g., hemispherical light distribution also called Lambertian distribution) such as in the case of floodlights (e.g., car headlight). In order to control light distribution, a light emitting apparatus has been proposed in which the side surface of a light emitting device is covered with a light reflection member.
For example, Japanese Patent Laid-Open Publication No. JP 2007-19096 A discloses this type of light emitting apparatus 900. FIG. 12 is a cross-sectional view of this light emitting apparatus 900. The light emitting apparatus 900 is composed of an LED element 901, and a case 904 formed of ceramics on which the LED element 901 is mounted. The case 904 has an opening on the light output side. The LED element 901 is mounted in this opening. In addition, the opening of the case 904 is filled with a coating material 903 which contains light reflection particles. This coating material 903 covers the outside area of the LED element 901 except the light output surface.
In addition, a phosphor layer 902 is arranged on the external surface of the coating material 903, which is formed in the opening of the case and serves as the light output surface. The phosphor layer 902 is composed of resin including a phosphor such as YAG (Yttrium Aluminum Garnet) which is excited by light emitted from the LED element 901 (blue light) and emits wavelength-converted light (yellow light). The phosphor layer 902 is constructed covering the entire light output surface of the LED element 901. In addition, the phosphor layer 902 has a light emission surface which is exposed on the light output side. The primary light (blue light) from the LED element 901 is mixed with the secondary light (yellow light), which is emitted by wavelength conversion of a part of this primary light so that white light is output from the light emission surface.
WO 2009/069671 and Japanese Patent Laid-Open Publication No. JP 2009-218274 A disclose light emitting apparatuses which include light emitting device mounted on a flat plate member. FIG. 13 shows the light emitting apparatus 910 disclosed in WO 2009/069671. The light emitting apparatus 910 includes a transparent member 913 including a phosphor on the upper surfaces of the light emitting devices 912. The phosphor converts the wavelength of light emitted from the light emitting device 912. The side surfaces of the light emitting devices 912 and the transparent member 913 are covered with the light reflective material 914.
Also Japanese Patent Laid-Open Publication Nos. JP H05-29665 A and JP 2009-182307 A disclose light emitting apparatuses including a frame which is formed of white resin and surrounds a light emitting device, and a transparent sealing resin with which the inner area of the frame is filled.
As stated above, in the Japanese Patent Laid-Open Publication No. JP 2007-19096 A, WO 2009/069671, and the Japanese Patent Laid-Open Publications Nos. JP 2009-218274 A, JP H05-29665 A and JP 2009-182307 A, methods are proposed for forming the light reflective resin which covers the side surface of the light emitting device.
However, in the case of Japanese Patent Laid-Open Publication No. JP 2007-19096 A, to form the opening in the case formed of ceramics with high heat dissipation so that the opening is filled with the light reflective resin, a partial removing process or the like is required which removes a part of ceramic sheet to form the opening. In this case, the number of production process increases. In addition, the processing precision is not high in the process for forming the opening in ceramics. For this reason, the production yield may decrease, or the production cost may increase.
Also, in the methods of WO 2009/069671 and Japanese Patent Laid-Open Publication No. 2009-218274, although the light reflective resin is formed on the flat plate member without forming such an opening, the productivity is not sufficient. For example, in the case where a frame is formed of the same material as the plate member, and holds the light reflective resin in the frame, the production yield may decrease, or the production cost may increase similar to Japanese Patent Laid-Open Publication No. JP 2007-19096 A. Also, in the case where the light reflective resin is formed by using the frame and then removing the frame, a part of the light reflective resin may be peeled off from the plate member together with the frame when the frame is removed.
Also, in the cases of Japanese Patent Laid-Open Publication No. JP 2007-19096 A, WO 2009/069671, and the Japanese Patent Laid-Open Publications Nos. JP 2009-218274 A, JP H05-29665 A and JP 2009-182307 A, although the light emitting device is covered with white resin, or an electrically conductive pattern is formed which allows current to flow into the light emitting device covered with white resin, the electrical resistance is not sufficiently low, or the bonding strength between white resin and the plate member is not sufficient.
Thus, a need exists for new light emitting apparatuses that can provide increases bonding strength between the base member and the resin member while keeping electrical resistance low.